LOW FRICTION MULTI STAGE THRUST BEARING
A thrust bearing having a circular cage with rolling elements disposed in at least some of pockets formed in the cage, upper and lower raceways having inward-facing surfaces disposed adjacent to the cage so that a first plurality of rolling elements is in rolling contact with the upper and lower raceways when the thrust bearing is in a first load condition and a second plurality of rolling elements is in rolling contact with the upper and lower raceways when the thrust bearing is in a second load condition.
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The following documents are incorporated herein by reference as if fully set forth: U.S. Provisional Patent Application No. 62/022,943, filed Jul. 10, 2014.
FIELD OF INVENTIONThe present invention relates to a bearing arrangement for thrust loads.
BACKGROUNDThrust bearings are known to support axial loads. Typical thrust bearings include spherical or cylindrical rolling elements arranged in a cage between two raceways. Generally, spherical rolling elements provide low friction and are suitable for low load conditions while cylindrical rolling elements tend to have greater energy loss and wear due to sliding but provide higher load carrying capacity.
Accordingly, a need exists for a thrust bearing that provides low friction and high load carrying capacity.
SUMMARYA thrust bearing providing enhanced friction characteristics and load carrying capacity is provided. In one embodiment, a thrust bearing is provided that comprises a circular cage having an upper cage surface and a lower cage surface with a thickness therebetween, and pockets formed through the thickness. Rolling elements are disposed in at least some of the pockets, with the rolling elements having a diameter greater than the thickness of the cage. Upper and lower raceways having inner and outer diameters and an intermediate portion between the inner and outer diameters formed with an inward-facing surface and an outward-facing surface are disposed on either side of the cage. The inner-facing surface of the upper raceway is disposed adjacent to the upper cage surface and the inner-facing surface of the lower raceway is disposed adjacent to the lower cage surface. In this configuration, a first plurality of rolling elements is in rolling contact with the upper and lower raceways when the thrust bearing is in a first load condition and a second plurality of rolling elements is in rolling contact with the upper and lower raceways when the thrust bearing is in a second load condition.
Other and further embodiments of the present invention are described below.
Embodiments of the present invention, briefly summarized above and discussed in greater detail below, can be understood by reference to the illustrative embodiments of the invention depicted in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting in scope, for the invention may admit to other equally effective embodiments.
Certain terminology is used in the following description for convenience only and is not limiting. The words “upper” and “lower” designate directions in the drawings to which reference is made. The words “inner-facing” and “outer-facing” refer to directions toward and away from the center of the part being referenced. “Axially” refers to a direction along the axis of a shaft or other part. The terminology includes the words specifically noted above, derivatives thereof and words of similar import.
In some embodiments the pockets 110 are arranged circumferentially spaced apart on two or more pitch diameters, for example on three pitch diameters 202, 204, and 206 as illustrated in
Rolling elements 112 are disposed in at least some of the pockets 110 and supported for rotation within the respective pocket. The cage 102 is illustrated with circular pockets 110 and spherical rolling elements 112 for ease of illustration only. The rolling elements 112 could also be cylindrical rolling elements and the pockets 110 rectangular in shape, or a combination of spherical and cylindrical rolling elements.
As shown in
In the embodiment illustrated in
In the non-limiting embodiment of
In some embodiments the pockets 610 are arranged circumferentially spaced apart on two or more pitch diameters, for example on three pitch diameters 702, 704, and 706 as illustrated in
In the embodiment illustrated in
Alternately, the inward-facing surfaces 602 could be radially inwardly divergent (not shown) under a first load condition and urged towards each other under a second load condition as described above.
The illustrations of
The cylindrical rolling elements 914 may alternate with spherical rolling elements 912 in any pattern along a pitch diameter 916. In a non-limiting embodiment illustrated in
The upper and lower raceways 820, 822 function as described above with regard to upper and lower raceways 120, 122, maintaining a curved configuration as in
In the second load condition of
Thus a thrust bearing which may provide the benefit of increased load-carrying capacity with reduced overall friction over known thrust bearing constructions is provided herein. In some embodiments, the increased load-carrying capacity and reduced friction are realized by distributing increasing loads over increasing surface areas by engaging a greater number of spherical rolling elements. In some embodiments, the benefit is realized by using both spherical and cylindrical rolling elements and limiting surface contact with cylindrical rollers, known to have higher energy losses than spherical rolling elements, at low load levels. At high load levels, the surface contact with the cylindrical rollers, known to have high load-carrying capability, is increased.
Having thus described the present invention in detail, it is to be appreciated and will be apparent to those skilled in the art that many physical changes, only a few of which are exemplified in the detailed description of the invention, could be made without altering the inventive concepts and principles embodied therein. It is also to be appreciated that numerous embodiments incorporating only part of the preferred embodiment are possible which do not alter, with respect to those parts, the inventive concepts and principles embodied therein. The present embodiment and optional configurations are therefore to be considered in all respects as exemplary and/or illustrative and not restrictive, and all alternate embodiments and changes to this embodiment which come within the meaning and range of equivalency of said claims are therefore to be embraced therein.
Claims
1. A thrust bearing comprising:
- a circular cage having an upper cage surface and a lower cage surface with a thickness therebetween, and pockets formed through the thickness;
- rolling elements disposed in at least some of the pockets, the rolling elements having a diameter greater than the thickness;
- upper and lower raceways each having inner and outer diameters and an intermediate portion between the inner and outer diameters formed with an inward-facing surface and an outward-facing surface,
- wherein the inward-facing surface of the upper raceway is disposed adjacent to the upper cage surface and the inner-facing surface of the lower raceway is disposed adjacent to the lower cage surface so that a first plurality of rolling elements is in rolling contact with the upper and lower raceways when the thrust bearing is in a first load condition and a second plurality of rolling elements is in rolling contact with the upper and lower raceways when the thrust bearing is in a second load condition.
2. The bearing of claim 1, wherein the pockets are disposed on at least a first pitch diameter and a second pitch diameter.
3. The bearing of claim 2, wherein the pockets disposed on the first pitch diameter are angularly offset from the pockets disposed on the second pitch diameter.
4. The bearing of claim 1, wherein the rolling elements are spherical rolling elements.
5. The bearing of claim 1, wherein the rolling elements are cylindrical rolling elements.
6. The bearing of claim 1, wherein at least some of the rolling elements are spherical rolling elements and at least some of the rolling elements are cylindrical rolling elements.
7. The bearing of claim 1, wherein the inward-facing surfaces of the raceways are convex and the outward-facing surfaces of the raceways are concave.
8. The bearing of claim 1, wherein the inward-facing surfaces of the raceways are radially divergent.
9. The bearing of claim 1, wherein the inward-facing surfaces of the raceways are radially convergent.
10. The bearing of claim 1, wherein the second plurality includes the first plurality.
11. A thrust bearing comprising:
- a circular cage having an upper cage surface and a lower cage surface with a thickness therebetween, and pockets formed through the thickness;
- rolling elements disposed in at least some of the pockets, the rolling elements having a diameter greater than the thickness;
- upper and lower raceways each having inner and outer diameters and an intermediate portion between the inner and outer diameters formed with an inward-facing convex surface and an outward-facing concave surface,
- wherein the inward-facing surface of the upper raceway is disposed adjacent to the upper cage surface and the inward-facing surface of the lower raceway is disposed adjacent to the lower cage surface so that a first plurality of rolling elements is in rolling contact with the upper and lower raceways forming a first contact area when the thrust bearing is in a first load condition and the same plurality of rolling elements is in rolling contact with the upper and lower raceways forming a second contact area when the thrust bearing is in a second load condition.
12. The bearing of claim 10, wherein the pockets are disposed on a pitch diameter.
13. The bearing of claim 10, wherein at least some of the rolling elements are spherical rolling elements.
14. The bearing of claim 10, wherein at least some of the rolling elements are cylindrical rolling elements.
Type: Application
Filed: Jun 10, 2015
Publication Date: Jan 14, 2016
Applicant: Schaeffler Technologies AG & Co. KG (Herzogenaurach)
Inventor: John Tate (Cornelius, NC)
Application Number: 14/735,433